+2009-01-02 Kenneth Zadeck <zadeck@naturalbridge.com>
+
+ PR rtl-optimization/35805
+ * df-problems.c (df_lr_finalize): Add recursive call to resolve lr
+ problem if fast dce is able to remove any instructions.
+ * dce.c (dce_process_block): Fix dump message.
+
2009-01-02 Mark Mitchell <mark@codesourcery.com>
PR 33649
/* Run the fast dce as a side effect of building LR. */
static void
-df_lr_finalize (bitmap all_blocks ATTRIBUTE_UNUSED)
+df_lr_finalize (bitmap all_blocks)
{
+ df_lr->solutions_dirty = false;
if (df->changeable_flags & DF_LR_RUN_DCE)
{
run_fast_df_dce ();
- if (df_lr->problem_data && df_lr->solutions_dirty)
+
+ /* If dce deletes some instructions, we need to recompute the lr
+ solution before proceeding further. The problem is that fast
+ dce is a pessimestic dataflow algorithm. In the case where
+ it deletes a statement S inside of a loop, the uses inside of
+ S may not be deleted from the dataflow solution because they
+ were carried around the loop. While it is conservatively
+ correct to leave these extra bits, the standards of df
+ require that we maintain the best possible (least fixed
+ point) solution. The only way to do that is to redo the
+ iteration from the beginning. See PR35805 for an
+ example. */
+ if (df_lr->solutions_dirty)
{
- /* If we are here, then it is because we are both verifying
- the solution and the dce changed the function. In that case
- the verification info built will be wrong. So we leave the
- dirty flag true so that the verifier will skip the checking
- part and just clean up.*/
- df_lr->solutions_dirty = true;
+ df_clear_flags (DF_LR_RUN_DCE);
+ df_lr_alloc (all_blocks);
+ df_lr_local_compute (all_blocks);
+ df_worklist_dataflow (df_lr, all_blocks, df->postorder, df->n_blocks);
+ df_lr_finalize (all_blocks);
+ df_set_flags (DF_LR_RUN_DCE);
}
- else
- df_lr->solutions_dirty = false;
}
- else
- df_lr->solutions_dirty = false;
}